Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by progressive functional and cell loss of neurons in the cerebellum, brain stem and spinal cord. The cause of SCA2 is CAG expansion in the ATXN2 gene resulting in polyglutamine (polyQ) expansion in the ataxin-2 protein. Patients with SCA2 are characterized by progressive cerebellar ataxia, slow saccadic eye movements and other neurologic features such as neuropathy (Pulst, S. M. (ed.), Genetics of Movement Disorders. Elsevier, Inc., Amsterdam, 2003, pp. 19-34.). Moderate CAG expansion in the ATXN2 gene is also associated with parkinsonism or amyotrophic lateral sclerosis (ALS) indistinguishable from the idiopathic forms of these diseases (Kim et al., Arch. Neurol., 2007, 64: 1510-1518; Ross et al., Hum. Mol. Genet., 2011, 20: 3207-3212; Corrado et al., Hum. Genet., 2011, 130: 575-580; Elden et al., Nature, 2010, 466: 1069-1075; Van Damme et al., Neurology, 2011, 76: 2066-2072).
The pathogenic functions of polyQ disease proteins that occur with polyQ expansion may be attributed to the gain of toxicity associated with the development of intranuclear inclusion bodies or with soluble toxic oligomers (Lajoie et al., PLoS One, 2011, 5: e15245). While SCA2 patient brains are characterized by loss of Purkinje cells, SCA2 Purkinje cells lack inclusion bodies indicating polyQ-expanded ataxin-2 may cause toxicity that is unrelated to inclusion body formation (Huynh et al., Ann. Neurol., 1999, 45: 232-241). Functions gained in polyQ-expanded ataxin-2 may include anomalous accumulation in Golgi bodies (Huynh et al., Hum. Mol. Genet., 2003, 12: 1485-1496), gain-of-normal functions (Duvick et al., Neuron, 2010, 67: 929-935) and sequestering of transcription factors (TFs) and glyceraldehyde-3-phosphate dehydrogenase like for other polyQ proteins (Yamanaka et al., Methods Mol. Biol., 2010: 648, 215-229; Koshy et al., Hum. Mol. Genet., 1996, 5: 1311-1318; Burke et al., Nat. Med., 1996, 2: 347-350). Some normal functions of ataxin-2 have been characterized. Ataxin-2 is present in stress granules and P-bodies suggesting functions in sequestering mRNAs and protein translation regulation during stress (Nonhoff et al., Mol. Biol. Cell, 2007, 18: 1385-1396). Ataxin-2 overexpression interfered with the P-body assembly, while underexpression interfered with stress granule assembly (Nonhoff et al., Mol. Biol. Cell, 2007, 18: 1385-1396). Interactions with polyA-binding protein 1, the RNA splicing factor A2BP1/Fox1 and polyribosomes further support roles for ataxin-2 in RNA metabolism (Shibata et al., Hum. Mol. Genet., 2000, 9: 1303-1313; Ciosk et al., Development, 2004, 131: 4831-4841; Satterfield et al., Hum. Mol. Genet., 2006, 15: 2523-2532). Ataxin-2 is a regulator of EGF receptor internalization and signaling by the way of its interactions with SRC kinase and the endocytic protein CIN85 (Nonis et al., Cell Signal., 2008, 20: 1725-1739). Ataxin-2 also interacts with the ALS-related protein TDP-43 in an RNA-dependent manner and familial and sporadic ALS associates with the occurrence of long normal CAG repeat expansion ATXN2 (Elden et al., Nature, 2010, 466: 1069-1075; Van Damme et al., Neurology, 2011, 76: 2066-2072).
Currently there is a lack of acceptable options for treating such neurodegenerative diseases. It is therefore an object herein to provide methods for the treatment of such diseases.